Complex shape structure for liquid lithium first walls of fusion power reactor environments

ABSTRACT

A method, system, and apparatus are disclosed for a complex shape structure for liquid lithium first walls of fusion power reactor environments. In particular, the method involves installing at least one tile on the surface area of the internal walls of the reactor chamber. The tile(s) is manufactured from a high-temperature resistant, porous open-cell material. The method further involves flowing liquid lithium into the tile(s). Further, the method involves circulating the liquid lithium throughout the interior network of the tile(s) to allow for the liquid lithium to reach the external surface of the tile(s) that faces the interior of the reactor chamber. In addition, the method involves outputting the circulated liquid lithium from the tile(s). In one or more embodiments, the reactor chamber is employed in a fusion reactor. In some embodiments, the tile is manufactured from a ceramic material or a metallic foam.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional application of, and claims the benefitof, U.S. patent application Ser. No. 13/078,729, filed Apr. 1, 2011,which is hereby incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates to complex shape structures. Inparticular, it relates to complex shape structures for liquid lithium(Li) first walls of fusion power reactor environments.

SUMMARY

The present disclosure relates to an apparatus, system, and method for acomplex shape structure for liquid lithium first walls of fusion powerreactor environments. In one or more embodiments, the disclosed methodfor maintaining liquid lithium on a surface area of internal walls of areactor chamber involves installing at least one tile on the surfacearea of the internal walls of the reactor chamber. At least one tile ismanufactured from a high-temperature resistant, porous open-cellmaterial. The disclosed method further involves flowing liquid lithiuminto at least one tile. In addition, the method involves circulating theliquid lithium throughout an interior network of the tile(s) to allowfor the liquid lithium to reach the external surface of the tile(s) thatfaces the interior of the reactor chamber. The method also involvesoutputting the circulated liquid lithium from the tile(s).

In one or more embodiments of the present disclosure, the reactorchamber is employed in a fusion reactor. The tile may be manufactured tobe of various shapes including, but not limited to, irregular shapes andregular shapes. In addition, the tile may be manufactured from varioushigh-temperature, porous materials including, but not limited to,various types of ceramic materials and metallic foams.

In at least one embodiment, at least one tile contains at least one opencell in the interior of the tile(s). Liquid lithium is circulatedthroughout the interior of the tile(s) via the open cell(s). In one ormore embodiments, at least one tile has a constant porosity. In someembodiments, at least one tile has a varied porosity.

In one or more embodiments, at least one tile includes an input plenum,where liquid lithium is inputted into the tile(s) via the input plenum.In at least one embodiment, at least one tile includes an output plenum,where liquid lithium is outputted from the tile(s) via the outputplenum. In some embodiments, the input plenum and/or the output plenumare each a hollow piece of metal. In one or more embodiments, the flowrate of the circulation of the liquid lithium within the interiornetwork of at least one tile is varied over time. In addition, in someembodiments, the flow rate of the circulation of the liquid lithiumdiffers from tile to tile.

In at least one embodiment, the system for maintaining liquid lithium ona surface area of internal walls of a reactor chamber includes at leastone tile and a reactor chamber. In one or more embodiments, at least onetile is manufactured from a high-temperature resistant, porous open-cellmaterial. In some embodiments, at least one tile is installed on thesurface area of the internal walls of the reactor chamber. In at leastone embodiment, at least one tile allows for liquid lithium to be flowedinto the tile(s). In addition, the tile(s) further allows for the liquidlithium to be circulated throughout the interior network of the tile(s)to allow for the liquid lithium to reach the external surface of thetile(s) that faces the interior of the reactor chamber. Additionally,the tile(s) further allows for the circulated liquid lithium to beoutputted from the tile(s).

In one or more embodiments, a tile for maintaining liquid lithium on asurface area of internal walls of a reactor chamber is disclosed. In atleast one embodiment, the tile is manufactured from a high-temperatureresistant, porous open-cell material. In some embodiments, the tileincludes at least one open cell in an interior of the tile forcirculating the liquid lithium within the interior of the tile.

The features, functions, and advantages can be achieved independently invarious embodiments of the present inventions or may be combined in yetother embodiments.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1 is an illustration of the interior of a toroidal fusion powerreactor, in accordance with at least one embodiment of the presentdisclosure.

FIG. 2 shows a top view of a single tile for maintaining liquid lithiumon the surface area of the internal walls of a reactor chamber, inaccordance with at least one embodiment of the present disclosure.

FIG. 3 illustrates a top view of a configuration of four of the tiles ofFIG. 2 that are installed next to one another, in accordance with atleast one embodiment of the present disclosure.

FIG. 4 depicts a cross-sectional side view of a tile for maintainingliquid lithium on the surface area of the internal walls of a reactorchamber that has a uniform porosity, in accordance with at least oneembodiment of the present disclosure.

FIG. 5 illustrates a cross-sectional top view of the tile of FIG. 4, inaccordance with at least one embodiment of the present disclosure.

FIG. 6 shows a cross-sectional top view of a tile for maintaining liquidlithium on the surface area of the internal walls of a reactor chamberthat has a non-uniform porosity, in accordance with at least oneembodiment of the present disclosure.

DESCRIPTION

The methods and apparatus disclosed herein provide an operative systemfor complex shape structures. Specifically, this system relates tocomplex shape structures for liquid lithium first walls of fusion powerreactor environments. In particular, the disclosed system uses ahigh-temperature, high-porosity open-cell material to maintain liquidlithium in a fusion energy reactor, thereby reducing damage to theinternal reactor surfaces that have complex shapes. For example, theBoeing Rigid Insulation (BRI) material, which is a porous open-cellceramic material with a high temperature tolerance and a good materialcompatibility, may be employed by the disclosed system. In addition, thedisclosed system also provides for high-neutron flux exposure for thelithium for purposes of tritium breeding.

BRI material is a porous, ceramic, fiber insulating material thatcomprises a unique combination of ceramic fibers, which are sinteredtogether to form a low density, highly porous material with very lowthermal conductivity. In addition, BRI material exhibits a high tensilestrength and an outstanding dimensional stability. In particular, BRImaterial is manufactured from a combination of silica (SiO₂) and alumina(Al₂O₃) fibers, and boron-containing powders, which help to aid in thefusion and sintering of the silica and alumina fibers. The preponderanceof the insulative capability of the BRI material is provided by thesilica fiber and the alumina fiber orientation. The BRI materialexhibits very low thermal conductivity, particularly in thethrough-the-thickness direction. Further details discussing thecomposition of BRI and the method of producing BRI are disclosed in U.S.Pat. No. 6,716,782, which is expressly incorporated herein by reference.

There are known difficulties in maintaining plasma control in fusionenergy reactors. Among them, plasmas can be unstable at high powerdensities. Liquid lithium is known to help stabilize plasmas in reactorvessels. The plasma consists mostly of positive ions and negativeelectrons, and its outer sheath, near the reactor walls, is cooler thanits core. In the sheath, the ions have a higher probability of acquiringelectrons from the plasma and, thus, becoming neutral atoms than do ionsin the core. Neutral atoms cannot be confined by magnetic fields, thusneutral atoms have a high probability of crossing the magnetic fieldthat confines the plasma, and hitting the reactor vessel walls. In thisprocess, the neutral atoms carry some energy from the plasma to thewalls, thus causing a slight further cooling of the plasma sheath and aslight heating of the walls. In a fusion plasma, most of these neutralatoms are hydrogen, but other materials can be present, such as heliummade by the fusion reactions and heavy elements (contaminants) that canbe spalled off the reactor structure by accidental plasma impingement onthe structure. If the walls are made of high temperature-tolerantceramics or metals, the neutral atoms will stick to the walls for ashort time, then drift back into the plasma sheath. However, the atomsreentering the plasma sheath from the walls are now quite cold incomparison to the plasma sheath, thus they cause considerable cooling ofthe plasma in the sheath. Normally, the plasma sheath is cooler than theplasma core, but if the sheath is cooled too much, the differential intemperature between the plasma core and the sheath increases theinstability of the plasma. Lithium on the inside wall of the reactortends to absorb and not release neutral atoms that drift into it. Byabsorbing and holding the neutral atoms that contact the walls, thelithium prevents the atoms from getting back into the plasma sheath ascold atoms, which helps the sheath to stay warmer and makes the overallplasma more stable.

Currently, in experiments, liquid lithium is drizzled down the inside ofthe side walls of the reactor vessel from channels that lie just abovewhere the side walls are nearly vertical (i.e. the channels lie justabove the “equator” or midsection of the torus reactor vessel). Becauseof gravity, the liquid lithium does not stay in place, but rather runsdown the side walls of the vessel from the channels, and is collected byother channels and drains that lie farther down in the vessel thatremove the lithium. This particular method is able to coat the sidewalls of the vessel from the equator of the reactor to most of the waydown to its bottom because gravity causes the lithium to flow down fromthe channels to the bottom of the reactor. But, this method clearly isnot able to coat the side walls that are above the equator of thevessel. In the lowest parts of reactors, liquid lithium has also beenused in pools and on coarse horizontal screens, neither of which methodcan be effectively applied to the upper walls. The disclosed systemallows for liquid lithium to be maintained on the surface of all theinner walls of the reactor vessel.

An additional advantage of the use of lithium on the reactor walls isthat it is a low atomic number (low-Z) material. If high atomic number(high-Z) materials, such as iron from steel in reactor walls, enter intothe plasma, their atoms can become electronically excited by absorbingkinetic energy from ions in the plasma. Typically, the excited high-Zmaterials lose their extra energy by radiating it as electromagneticenergy (photons). The plasma is transparent to most wavelengths ofelectromagnetic energy; thus, most photons emitted by excited high-Zmaterials escape from the plasma and are absorbed by the reactor walls.The net effect is an overall energy loss from the plasma and is calledradiative cooling. The plasma gets colder and the reactor walls gethotter. That is the opposite of what is needed to maintain the fusionpower reactions. Low-Z materials, such as lithium, have so few electronsthat they have very few ways in which they can radiate energy,therefore, low-Z materials cause relatively little radiative cooling ofthe plasma.

A further advantage to the use of lithium on the insides of fusionreactor walls is that one of the two elements of reactor fuel, tritium,is very rare naturally, but can be made efficiently by exposing lithiumto the flux of high energy neutrons produced by the fusion reactor.Thus, if lithium can be placed in regions of the reactor close to theplasma where the neutron flux is most intense, the production of tritiumfrom the lithium can be efficient. Because of liquid lithium's tendencyto hold on to atoms of other materials in it, cycling the lithiumthrough the reactor provides an effective way to introduce pure lithiuminto the reactor, produce tritium in the lithium, and remove the tritiumfrom the reactor by pumping the tritiated lithium back out of thereactor and passing it through a chemical processing system thatextracts the tritium from the lithium, thus providing tritium to fuelthe reactor and clean lithium ready to be cycled once more through thereactor.

The system of the present disclosure utilizes a porous, open-cellmaterial that is capable of retaining liquid lithium in place on reactorvessel walls against gravity and electromagnetic forces. In addition,this material allows for the liquid lithium to be slowly pumpedthroughout the system in order to absorb contaminants from the plasma.During operation of the disclosed system, clean lithium is first pumpedinto the system to the inner surfaces of the reactor walls, where thelithium is exposed to the plasma. In that location, the clean lithiumabsorbs contaminants from the plasma. The contaminated lithium is thenremoved from the reactor, and is processed to remove the plasmacontaminants from the lithium. After the contaminants are removed fromthe lithium, the cleaned lithium is re-circulated back into the system.

Liquid lithium surfaces exposed to the plasma inside experimentaltokamaks and other types of fusion energy experimental devices have beenshown to help stabilize the plasma and to help the plasma maintain itshigh internal temperature. However, it should be noted that thesereactor vessels typically are constructed to have very complex shapes aswell as having many discontinuities and openings for various items, suchas for instruments, vacuum pumping ports, and magnetic coils. Currently,no effective methods have been proposed for retaining liquid lithium onthe inside of the reactor vessel walls that accommodates all thediscontinuities and openings, and which retains the lithium against theeffects of gravity and electromagnetic forces. The present disclosureteaches a method which can accommodate discontinuities, and which keepsslowly flowing liquid lithium in place on reactor walls regardless ofthe orientation of the reactor wall surface, and the effects of gravityand electromagnetic forces.

To date, experiments with liquid lithium adjoining fusion plasmas havebeen more focused on the effect of lithium on the plasma than on how tobuild a liquid lithium wall. Therefore, four types of ad hoc approacheshave been used to facilitate liquid lithium-hydrogen plasma interactionexperiments. These four approaches are: (1) pools of liquid lithiumplaced in trays at the bottom of the toroidal reactor vessel, (2) metalscreens wetted with liquid lithium that are placed horizontally at thebottom of the vessel, (3) a band placed about the mid-plane of thereactor vessel has liquid lithium flowing down its inner surface fromthe top of the band to the bottom of the band, and (4) confining theplasma in spherical and cylindrical reactor vessels that are physicallyrotated so as to cause the liquid lithium to continually recoat theinner surface walls of the vessel from a pool at the bottom of thevessel.

The first two listed approaches have limitations of only producinglithium surfaces for a small area in the bottom of the reactor. Thethird approach only coats a band about the middle of the reactor, andrequires high flow rates to keep the surface of the band coated. Highflow rates increases the pumping power required to operate the reactor,which subtracts from any energy the reactor might produce. The fourthapproach is not being easily being employed by a toroidal vessel, whichhas the most effectively shaped magnetic fields for containing plasmas.Continually rotating the walls of a toroidal vessel is impossiblebecause of the rigid materials used for the construction of thesevessels. In addition, the fourth approach requires portions of theinside of the reactor vessel to constantly move, which interferes withthe placement and the use of other devices that must be present withinthe vessel wall, such as vacuum pumping ports, sensors, and magneticcoils.

The present disclosure employs tiles manufactured from high-temperature,open-cell sponge-like material (e.g., the Boeing Rigid Insulation (BRI)material) to retain liquid lithium in place against gravity andelectromagnetic forces, and to allow for the liquid lithium to be slowlypumped throughout the system in order to remove contaminants from theplasma. There are multiple advantages to this approach. A firstadvantage is that the tiles can be manufactured to be small in size sothat the inside of the toroidal vessel can be tiled with a mosaic ofliquid lithium filled tiles despite the complex shape of the inside ofthe reactor vessel. A second advantage is that the material of the tiles(e.g., a porous ceramic material with open cells) is resistant to thehigh temperatures to which the tiles will be exposed to when the plasmais present inside of the reactor vessel. A third advantage is that thematerial of the tiles (e.g., porous a ceramic material with open cells)is resistant to the corrosive effects of lithium. A fourth advantage isthat the construction of the tiles can be tailored to produce pore sizesand/or open channels that are optimal to the retention and flow ofliquid lithium.

In addition, a fifth advantage is that, if plasma disruptions cause theplasma to impact the tiles so intensely that the outer surface oflithium boils away, the high permeability of the tiles will allow morelithium to wick to the surface of the tile. A sixth advantage is that,in the event that some of the tile itself is removed by a plasma impact,the depth of the tile will allow for the tile to continue to functionand, thus, several plasma impacts on a tile can be tolerated before thetile would need to be replaced. A seventh advantage is that, in theevent that part of a tile is ablated by the plasma, the materials thatthe tile is manufactured from are mostly of low nuclear weight elements,which will have a less adverse effect on the plasma than materials ofhigh weight metals. An eighth advantage is that, in the event that aportion of a tile is ablated, the portion of the tile that is ablatedwill simply be an empty space filled with liquid lithium. As such, it isevident that the use by the disclosed system of tiles, which aremanufactured from a high-temperature, porous material, to retain liquidlithium on the reactor vessel walls has many beneficial advantages.

In the following description, numerous details are set forth in order toprovide a more thorough description of the system. It will be apparent,however, to one skilled in the art, that the disclosed system may bepracticed without these specific details. In the other instances, wellknown features have not been described in detail so as not tounnecessarily obscure the system.

FIG. 1 is an illustration of the interior of a fusion power reactor 100,in accordance with at least one embodiment of the present disclosure. Inthis figure, it can be seen that the fusion power reactor 100 is of atorus shape. It should be noted that the system of the presentdisclosure can be used with various different types and shapes of fusionpower reactors. The first wall of the fusion power reactor 100 is linedwith small tiles 110 that are each manufactured from a hightemperature-tolerant, porous material. These small tiles 110 allow forliquid lithium to coat the surface of the walls of the reactor vessel100. The liquid lithium helps to stabilize the plasma in the reactorvessel 100, and helps the plasma maintain its high internal temperature.

FIG. 2 shows a top view of a single tile 200 for maintaining liquidlithium on the surface area of the internal walls of a reactor chamber,in accordance with at least one embodiment of the present disclosure.The tile 200, which is manufactured from a high-temperature-resistant,porous material with open cells, is installed onto the reactor vesselwall 240. In this figure, the tile 200 is shown to include an inputplenum 260 and an output plenum 280. Both the input plenum 260 and theoutput plenum 280 are a single hollow piece of non-porous material(e.g., a metal).

During operation of the system, clean liquid lithium is inputted intothe tile 200 through the input plenum 260. The liquid lithium is flowedinto the input plenum 260 of the tile 200 via pressure being applied atthe input plenum 260 and/or a vacuum being present at the output plenum280. Various types of pumps may be employed by the system for applyingpressure at the input plenum 260 of the tile 200 including, but notlimited to, a propeller pump, a centrifugal pump, and a piston pump. Theclean liquid lithium circulates within the interior network of opencells or channels throughout the body 250 of the tile 200. The cleanliquid lithium seeps through the open cells of tile 200 to reach theporous external surface 220 of the tile 200 that faces the interiorcavity of the reactor vessel, which contains the hot, tenuous plasma230. The direction of the flow of the liquid lithium within the body 250of the tile 200 is denoted by arrow 270.

The clean liquid lithium that lies on the porous external surface 220 ofthe tile 200 absorbs contaminants from the plasma 230. This newlycontaminated liquid lithium is then removed from the tile 200 via theoutput plenum 280. After the contaminated liquid lithium is removed fromthe tile 200, the liquid lithium is processed to remove the contaminantsfrom the liquid lithium. The resulting cleaned liquid lithium is thenre-circulated back into the system.

It should be noted that in alternative embodiments, the tile 200 may notspecifically include an input plenum 260 and/or an output plenum 280 asis depicted in FIG. 2, but rather may have at least one open cell orchannel in its interior for the liquid lithium to be inputted into thetile 200 and/or to be outputted from the tile 200.

FIG. 3 illustrates a top view of a configuration 300 of four of thetiles 310 of FIG. 2 that are installed next to one another, inaccordance with at least one embodiment of the present disclosure. Inthis figure, it is shown that the tiles 310 are able to be installedadjacent to one another along the curved surface of the reactor vesselwall 330. When the tiles 310 are installed in this configuration, theporous external surface 340 of the tiles 310 that faces the interiorcavity of the reactor vessel containing the plasma 320 is shown to forma curved surface area.

FIG. 4 depicts a cross-sectional side view of a tile 410 for maintainingliquid lithium on the surface area of the internal walls of a reactorchamber that has a uniform porosity, in accordance with at least oneembodiment of the present disclosure. In this figure, the tile 410 isshown to have an input plenum 430 and an output plenum 440. The tile 410is also depicted to be manufactured to have a uniform porosity 420. Inaddition, the direction of the flow of the liquid lithium within thebody of the tile 410 is denoted by arrow 450 in this figure.

FIG. 5 illustrates a cross-sectional top view of the tile 410 of FIG. 4,in accordance with at least one embodiment of the present disclosure.This figure simply shows another cross-sectional view of the tile 410,which has a uniform porosity 420. In addition, it should be noted that,in some embodiments, the side areas 510, 520 of the tile 410 aremanufactured from the same non-porous material that is used tomanufacture the input plenum 430 and the output plenum 440.

FIG. 6 shows a cross-sectional top view of a tile 610 for maintainingliquid lithium on the surface area of the internal walls of a reactorchamber that has a non-uniform porosity, in accordance with at least oneembodiment of the present disclosure. In this figure, the tile 610 isshown to have an input plenum 630 and an output plenum 640. The tile 610is illustrated to be manufactured to have a non-uniform porosity 620. Inthis figure, the porosity of the body of the tile 610 is shown togradually lessen from the external surface 660 of the tile 610 thatfaces the plasma 670 to the input and output plenums 630, 640. Also inthis figure, arrow 650 illustrates the direction of the flow of theliquid lithium within the body of the tile 610.

Although certain illustrative embodiments and methods have beendisclosed herein, it can be apparent from the foregoing disclosure tothose skilled in the art that variations and modifications of suchembodiments and methods can be made without departing from the truespirit and scope of the art disclosed. Many other examples of the artdisclosed exist, each differing from others in matters of detail only.Accordingly, it is intended that the art disclosed shall be limited onlyto the extent required by the appended claims and the rules andprinciples of applicable law.

We claim:
 1. A system for maintaining liquid lithium on a surface areaof internal walls of a reactor chamber, the system comprising: at leastone tile, wherein the at least one tile is manufactured from ahigh-temperature resistant, porous open-cell material; and the reactorchamber, wherein the at least one tile is installed on the surface areaof the internal walls of the reactor chamber, wherein the at least onetile allows for liquid lithium to be flowed into the at least one tile,wherein the at least one tile further allows for the liquid lithium tobe circulated throughout an interior network of the at least one tile toallow for the liquid lithium to reach an external surface of the atleast one tile that faces the interior of the reactor chamber, andwherein the at least one tile further allows for the circulated liquidlithium to be outputted from the at least one tile.
 2. The system ofclaim 1, wherein the reactor chamber is employed in a fusion reactor. 3.The system of claim 1, wherein the high-temperature resistant, porousmaterial is a ceramic material.
 4. The system of claim 1, wherein thehigh-temperature resistant, porous material is a metallic foam.
 5. Thesystem of claim 1, wherein the at least one tile comprises at least oneopen cell in an interior of the at least one tile, wherein the at leastone open cell allows for the liquid lithium to be circulated throughoutthe interior of the at least one tile.
 6. The system of claim 1, whereinthe at least one tile has one of an irregular shape or a regular shape.7. The system of claim 1, wherein the at least one tile has one of aconstant porosity or a varied porosity.
 8. The system of claim 1,wherein the at least one tile includes an input plenum, wherein theliquid lithium is inputted into the at least one tile via the inputplenum.
 9. The system of claim 8, wherein the input plenum is a hollowpiece of metal.
 10. The system of claim 1, wherein the at least one tileincludes an output plenum, wherein the liquid lithium is outputted fromthe at least one tile via the output plenum.
 11. The system of claim 10,wherein the output plenum is a hollow piece of metal.
 12. The system ofclaim 1, wherein a flow rate of the circulation of the liquid lithiumwithin the interior network of the at least one tile is varied overtime.
 13. A tile for maintaining liquid lithium on a surface area ofinternal walls of a reactor chamber, the tile comprising: ahigh-temperature resistant, porous open-cell material; and at least oneopen cell in an interior of the tile for circulating the liquid lithiumwithin the interior of the tile.
 14. The tile of claim 13, wherein thehigh-temperature resistant, porous material is a ceramic material. 15.The tile of claim 13, wherein the high-temperature resistant, porousmaterial is a metallic foam.
 16. The tile of claim 13, wherein the tilecomprises at least one open cell in an interior of the tile, wherein theat least one open cell allows for the liquid lithium to be circulatedthroughout the interior of the tile.
 17. The tile of claim 13, whereinthe tile has one of an irregular shape or a regular shape.
 18. The tileof claim 13, wherein the tile has one of a constant porosity or a variedporosity.
 19. The tile of claim 13, wherein the tile includes an inputplenum, wherein the liquid lithium is inputted into the tile via theinput plenum.
 20. The tile of claim 13, wherein the tile includes anoutput plenum, wherein the liquid lithium is outputted from the tile viathe output plenum.